Study Set Content:
Weak acids
Formic acid, acetic acd, Trichloroacetic acid, Hydrofluoric
Weak base
Ammonia, Trimethyl ammonia, Pyridine, Ammonium hydroxide
A substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or stomach upset.
Antacid
5 Examples of antacids available in the Philippine market.
• Gaviscon
• Amphogel
• Alamag
• Mylanta
Henderson-Hasselbalch equation
are solutions that resist changes in pH, upod addition of small amounts of acid or base.
Buffer
Has working pH range and capacity which dictate how much acid/base can be neutralized before pH changes, and the amount by which it will change.
Buffer
What are the criteria to consider when selecting a buffer?
pKa, solubility, membrane impermeable, minimal salt effects,
influences on dissociation, ionic strength, cation, interactions
and stability, biochemical inertness, optical absorbance, ease
and cost.
List down five (5) commonly used buffers in pharmacy.
• Phosphoric acid
• Citric acid
• Acetic acid
• Aspartic acid
• Malic acid
The ratio of the equilibrium concentration (ci) of a dissolved
substance in a two-phase system consisting of two largely
immiscible solvents or partially miscible liquids.
Partition coefficient (P)
If c1 and c2 are the concentrations of this substance in the two
layers, then:
the quotient of twoconcentration and is usually given in the form of its logarithm to base 10 (log P).
partition coefficient (P)
Methods of measuring distribution coefficients
1. Shake flask-type
2. HPLC-based
3. pH-metric
Factors affecting partition coefficient:
• Polarity
• Temperature
• pH
Is a mixture of two substances, one of which the dispersed
phase is distributed in form of subdivided particles
throughout another substance (continuous phase, dispersion
medium).
Dispersion (dispersed system)
Types of dispersion
▪ Molecular dispersions
▪ Colloids
▪ Coarse dispersion (suspensions)
Means settling of particle (or) floccules occur under
gravitational force in liquids dosage form.
Sedimentation
Velocity of sedimentation expressed by
Stoke’s equation
Characteristics of an Ideal Suspension:
1. It should settle slowly and should be readily redispersed on (blank) of the container.
gentle shaking
The particle size of the suspension remainso (blank) throughout its long period of undisturbed standing.
fairly constant
